Fluid pressure actuated switch



May 23, 1967 D. A. REISE ETAL FLUID PRESSURE ACTUATED SWITCH Filed July 26, 1965 INVENTORS DONALD A. REISE CHARLES W. JEEP, JR. A ATTORNEY .ary contacts will be closed United States Patent 3,321,594 FLUID PRESSURE ACTUATEID SWITCH Donald A. Reise, St. Louis, and Charles W. Jeep, In,

Webster Groves, Mo., assignors to ACE Industries, In-

corporated, New York, N.Y., a corporation of New Jersey Filed July 26, 1965, Ser. No. 474,715 3 Claims. (Cl. 290-83) This invention relates to fluid pressure actuated switches for electrical circuits and consists particularly in a novel safety switch which responds to the presence or absence of normal operating pressure in the oil feed line of an engine.

Fluid pressure actuated switches find utility in a number of applications. One application of importance to this invention is the use of a fluid pressure actuated electrical switch in the circuit of an electrical fuel pump when used on an automotive vehicle. In such an installation the pump motor is energized when the ignition circuit is closed. However, it is undesirable that the fuel pump be operating in the event that the engine is not running or in case the oil pressure falls below a safe operating level. Safety considerations make it imperative that in the event a vehicle equipped with an electric fuel pump is involved in an accident, that the pump cease pumping as soon as possible, even though the ignition switch is not turned to the off position. An example of this condition would be one in which the vehicle is overturned, in which case the enginewould soon stop running, but the ignition switch might not be turned oif immediately by the driver.

It is an object of the present invention to provide a small, compact, low-cost, dependable fluid pressure actuated electrical switch.

Another object is to provide such a switch in which the actuator element has adequate movement to compensate for wear and inaccuracies of manufacture.

Still another object is to provide such a switch having a switch actuating diaphragm with means for positively limiting the throw of the diaphragm to prevent excessive distortion thereof.

Still another object is to provide a switching action which causes wiping action between the switch points to insure better contact therebeween.

Yet another object is to provide a pressure actuated switch that is sensitive and will operate properly under wide variation of pressures produced by an engine lubricating system under the dilferent operating conditions of the vehicle.

Still another object is to provide a novel pressure switch of the double contact type in which the respective stationwhen there is a pressure and when there is an absence of pressure in the system.

These and other more detailed objects and advantages will be apparent from an examination of the following specification, the claims, and the accompanying drawings in which:

FIGURE 1 is a top view-of the switch; FIGURE 2 is a vertical center section therethrough; FIGURE 3 is a cross section taken along the lines 3-3 of FIGURE 2;

FIGURE 4 is another vertical section of the switch; FIGURE 5 is a schematic electrical diagram illustrating the method of installation of the switch.

Referring now to the drawing and to FIGURES 1 through 4 in particular, there is shown the switch of the invention. The switch comprises a top cap member having electrodes 12, 14 and 16 thereon. A vent passage 15 can be provided alongside one or more of the electrodes if desired to permit free entry and egress of air to the space above a diaphragm 30. Cap 10 is preferably made of an electrically nonconductive or insulating material such as rubber, Bakelite, or plastic. The cap 10 is fitted into a recess in a lower body member 20, which is provided with pipe threads 22 at the lower end thereof. An axial passage 24 provides communication for fluid pressure to actuate the switch.

The body 20 is provided with a recess 26 for receiving a portion of cap member 10. A diaphragm 30 is placed at the bottom of recess 26 and rests upon a shoulder 32. The lower portion of cap 10 presses upon the diaphragm to position and hold it in place and make a fluidtight seal. The bottom portion of cap 10 is secured by an overturned lip 34 of the body 20. If desired, the outer surface of body 20 can be provided with a hexagonal section 36 for engagement by a wrench to facilitate installation or removal of the switch. The interior of the body 20 is provided with a conical recess 40 below the diaphragm to limit the movement of the diaphragm. The interior of cap member 10 is generally hollowed out and one portion of the interior provides a shoulder 42. An axial recess 44 receives and positions a spring 46. A movable contact arm 50 is secured to the inner end of electrode 14. Contact arm 50 is provided with a double ended contact point 51. Contact arm 50 is provided near its center with a dimple or depression 51 for receiving on one side the conical portion 54 of a piston 56, and on its other side one end of spring 46 to center and position the same. A portion 53 may be cut away to impart greater flexibility to contact arm 50.

Upper and lower fixed contacts 60, 62, having contact points 64, 66, are secured to electrodes 12 and 16 respectively.

In operation, when fluid pressure from the oil pump of the engine is applied to the conduit 24, the diaphragm 30 will be raised and the piston 56 will rise with it. At that time the center contact 50 will move upwardly to close the circuit with fixed contact 60' by way of points 64 and 51. Spring 46 resists the upward movement of piston 56 and thus governs the pressure at which the switch will operate. As shown in FIGURE 2, it is seen that the outer end of contact 50 is flexed slightly upward, and as the piston 56 moves the contacts apart, the electrode first straightens out and in so doing imparts a rolling and sliding motion to the contact points 51, 66, thus tending to wipe them clean. When the piston rises to its uppermost position, a similar action will take place as between contact points 51 and 64. Shoulder 42 in cap 10 limits the upward movement of piston 56 so that no undue stresses will be placed on any portion of the switch, particularly the diaphragm.

Referring to FIGURE 5, the switch is shown schematically as it would be installed in a motor vehicle. A battery 70, grounded at 71, supplies voltage to an ignition switch 72 and to a vehicle starting motor 73. When switch 72 is rotated, contacts 74, 75 will be closed completing a circuit to contact 76, and this in turn completes a circuit to contact 77, which energizes a starting solenoid 78. This closes switch 79 to energize the starting motor 73. Current is passed by Way of contact 77 through wire 80 to contact 62, through movable contact 50, to a wire 81, which supplies electric current to the motor 82 of the electric fuel pump, thus causing the pump to deliver fuel to the carburetor of the engine. When the engine is running, the oil pump 84 of the engine will deliver fluid pressure to the switch by way of a pipe 85, and will shift the electrical circuit by way of contact 50 to complete the circuit with contact 60 and Wire 92 to contact 76, and the fuel pump 82 will continue to run. After the engine has started, the ignition switch will be turned to the normal running position, so that contacts 90, 91 complete a circuit to contact 76 and the fuel pump is thus able to continue running but the starter solenoid 78 is deenergized and the starting motor will cease to operate.

Also shown is a low oil pressure warning light 93 such as is commonly used on modern automobiles. In the event of low oil pressure, or a stopped engine, contacts 51, 64 will open and battery current will pass through the lamp 93 to motor 82 and thence to ground. The high resistance of the lamp will limit current flow so that motor 82 will not run.

What is claimed is:

1. A fluid pressure actuated switch comprising (A) an upper housing of electrically nonconductive material,

(*B) a lower housing fastened to said upper housing,

(C) a diaphragm interposed between said upper and lower housings and secured at its outer periphery by said housings,

(D) an axial bore in said lower housing for communicating a source of pressure with one side of the said diaphragm,

('E) a recess within said upper housing, said recess containing a movable contact, a normally closed contact and a normally open contact,

(F) a plurality of electrodes extending through the said upper housing, one for each of said contacts, the said electrodes having means at their outer ends for securing an electrical conductor thereto and at their inner ends for securing one of the said contacts thereto, V

(G) a spring centrally disposed in said recess and secured from lateral movement,

(H) a circumferential shoulder in said recess spaced a predetermined distance from the lower edge of said upper housing,

(I) a piston in said recess, said piston having an enlarged lower portion engaging the said diaphragm on one side and having a portion of reduced size at its upper end, said reduced portion also engaging a securing means in said movable contact to prevent lateral movement thereof, the said enlarged lower portion being confined also by the said recess whereby movement of the said piston on application of fluid pressure will be limited by the said circumferential recess,

(1) the said normally open and normally closed con-- tacts being spaced apart a distance less than the length of travel of said piston whereby. a rolling and sliding motion is imparted to the surfaces of the contacts during movement of said piston from one position to another.

2. A fluid pressure actuated switch comprising (A) an upper housing of electrically nonconductive material,

(B) a lower housing fastened to said upper housing,

(C) a diaphragm interposed between said upper and said lower housings and secured at its outer periphery by said housings,

(D) a conical depression in an upper portion of said lower housing,

(B) an axial bore in said lower housing for communicating a source of pressure with said depression,

(F) a recess within said upper housing, said recess containing an upper stationary normally open contact, an intermediate movable contact, and a lower stationary normally closed contact,

(G) a plurality of electrodes extending through the said upper housing, each of said electrodes having means at their outer ends for securing an electrical conductor thereto and at their inner ends for securing one of said contacts thereto,

(1) a first one of the said electrodes being located off-center to one side of the said upper housing and having the said movable contact secured thereto,

(2) the other two -of the said electrodes being spaced apart and located more centrally of the said upper housing, each having a stationary contact secured thereto,

(H) a vent passage in said upper housing adjacent one of the said electrodes,

(1) biasing means centrally disposed in said recess and secured from lateral movement therein, said biasing means being interposed between the bottom of said recess and an upper face of said movable contact, the said movable contact being further provided with locating means for said biasing means constituting a depression when viewed from the underside and a raised portion or dimple when viewed from the upper side thereof,

(1) a circumferential shoulder in said recess spaced a predetermined distance from the lower edge of said upper housing,

(K) a piston in said recess, said piston having an enlarged lower portion resting on said diaphragm, and a portion of reduced size at its upper end engaging the said dimple, said piston being limited in its movement by the said shoulder at one end of its travel and by the said diaphragm resting on the said conical depression at the other end of its travel.

3.A fluid pressure actuated switch comprising (A) an upper housing of electrically nonconductive material,

(B) a lower housing fastened to said upper housing,

(C) a diaphragm interposed between said upper and said lower housings and secured at its outer periphery by said housings,

(D) a conical depression in an upper portion of said lower housing,

(E) an axial bore in said lower housing for communicating a source of pressure with said depression,

(F) a recess within said upper housing, said recess containing an upper stationary normally open contact, an intermediate movable contact, and a lower stationary normally closed contact,

(G) a plurality of electrodes extending through the said upper housing, each of said electrodes having means at their outer ends for securing an electrical conductor thereto and at their inner ends for securing one of the said contacts thereto,

(1) a first one of the said electrodes being located off-center to one side of the said upper housing and having the said movable contact secured thereto,

(2) the other two of the said electrodes being spaced apart and located more centrally of the said upper housing, each having a stationary contact secured thereto,

(H) biasing means centrally disposed in said recess and secured from lateral movement therein, said biasing means being interposed between the bottom of said recess and an upper face of said movable contact, the said movable contact being further provided with locating means for said biasing means constituting a depression which viewed from the underside and a raised portion or dimple when viewed from the upper side thereof,

(1) a circumferential shoulder in said recess spaced a predetermined distance from the lower edge of said upper housing,

5 6 (I) a piston in said recess, said piston having an en- References Cited by the Examiner larged lower portion resting on said diaphragm, UNITED STATES PATENTS and a portion of reduced size at its upper end for engagement with the said dimple, said piston being 2,253,629 8/1941 KuPfel'schmld 20083 limited in its movement by the said shoulder at 5 2,849,242 8/1958 Alhson X one end of its travel and by the said diaphragm I resting on the said conical depression at the other BERNARD GILHEANY Pr'mary Emmmer' end of its travel. H. B. GILSON, G. MAIER, Assistant Examiners. 

1. A FLUID PRESSURE ACTUATED SWITCH COMPRISING (A) AN UPPER HOUSING OF ELECTRICALLY NONCONDUCTIVE MATERIAL, (B) A LOWER HOUSING FASTENED TO SAID UPPER HOUSING, (C) A DIAPHRAGM INTERPOSED BETWEEN SAID UPPER AND LOWER HOUSINGS AND SECURED AT ITS OUTER PERIPHERY BY SAID HOUSINGS, (D) AN AXIAL BORE IN SAID LOWER HOUSING FOR COMMUNICATING A SOURCE OF PRESSURE WITH ONE SIDE OF THE SAID DIAPHRAGM, (E) A RECESS WITHIN SAID UPPER HOUSING, SAID RECESS CONTAINING A MOVABLE CONTACT, A NORMALLY CLOSED CONTACT AND A NORMALLY OPEN CONTACT, (F) A PLURALITY OF ELECTRODES EXTENDING THROUGH THE SAID UPPER HOUSING, ONE FOR EACH OF SAID CONTACTS, THE SAID ELECTRODES HAVING MEANS AT THEIR OUTER ENDS FOR SECURING AN ELECTRICAL CONDUCTOR THERETO AND AT THEIR INNER ENDS FOR SECURING ONE OF THE SAID CONTACTS THERETO, (G) A SPRING CENTRALLY DISPOSED IN SAID RECESS AND SECURED FROM LATERAL MOVEMENT, (H) A CIRCUMFERENTIAL SHOULDER IN SAID RECESS SPACED A PREDETERMINED DISTANCE FROM THE LOWER EDGE OF SAID UPPER HOUSING, 